Oranjestad, February 14, 2011 - Transforming seaweed into fuel has been the dream of many a scientist, entrepreneur, and policy maker for years, particularly as debates have escalated over traditional biofuel crops—namely corn and sugar cane. Those biofuel sources compete with food crops for precious arable land and fresh water. Seaweed doesn't.
The great stumbling block for seaweed has been that standard microbes cannot readily metabolize its primary sugar constituent, known as alginate. Two other sugars found in seaweed ferment readily, but without conversion of the alginate, biofuel production from seaweed is simply too inefficient, and thus too expensive, to ever compete seriously with petroleum-based fuels.

Now, using synthetic biology and enzyme engineering, Adam Wargacki of Bio Architecture Lab in Berkeley, CA (USA), and his colleagues have made seaweed more palatable. The team has engineered a new form of E. coli bacteria that can digest all the sugars found in brown seaweed, including alginate.

Their fermentation experiments using the new microbe, reported today in the journal Science, successfully achieved 80% of seaweed's maximum theoretical ethanol yield, which is double that of sugar cane and five times that of corn. Whether the good work of this newly engineered microbe can be scaled up economically is the next question. Scientists still have to find a way to make biofuel production from seaweed lucrative.